Cells 1 Keratinizing epithelial cells 2 Wet stratified barrier epithelial cells

1. Cells • 1 Keratinizing epithelial cells • 2 Wet stratified barrier epithelial cells • 3 Exocrine secretory epithelial cells • 4 Hormone secreting cells • 5 Metabolism and storage cells • 6 Barrier function cells (Lung, Gut, Exocrine Glands and Urogenital Tract) • 6.1 Kidney • 6.2 Other • 7 Epithelial cells lining closed internal body cavities • 8 Ciliated cells with propulsive function • 9 Extracellular matrix secretion cells • 10 Contractile cells • 11 Blood and immune system cells • 12 Sensory transducer cells • 13 Autonomic neuron cells • 14 Sense organ and peripheral neuron supporting cells • 15 Central nervous system neurons and glial cells • 16 Lens cells • 17 Pigment cells • 18 Germ cells • 19 Nurse cells • 20 Interstitial cells

2. 303 Fall 2011 Lecture 5 - Chapter 2 Cells of the Nervous System

3. 2 Types of Cells in NS Nerve Cells Glial Cells (Neurons) (Glia) Electrical Signaling Supportive Communicate with other cells No signaling (90%)

4. The NEURON • Life span: Good newextreme longevity (100 years) • Bad newsamitotic (except for hippocampus…new) • They all carry electro-chemical nerve signals • They do differ in structure…. • They do differ in function…but basic • setup is similar • CELL BODY • NUCLEUS • DENDRITES • AXON • TERMINAL

5. Differences between axons and dendrites:

6. Dendrites Axons

7. Neurons are similar to other cells in the body because: • Neurons are surrounded by a cell membrane • Neurons have a nucleus that contains genes • Neurons contain cytoplasm, mitochondria and other "organelles" • Neurons carry out basic cellular processes such as protein • synthesis and energy production • However, neurons differ from other cells in the body because: • Neurons have specialized extensions called dendrites and axons • Neurons communicate with each other - electrochemical • Neurons contain some specialized structures (synapses) and • chemicals (neurotransmitters) The NEURON

8. Organelles of the Neuron

9. Organelles of the Neuron regulates water, nutrients and wastes, ions, receptors Rough ER: Protein export Smooth ER: cell membrane DNA Packaging in vesicles   power plants - ATP - energy protein synthesis (translation) enzymes - digestion of nutrient molecules

10. Organelles of the Neuron

11. Types of neurons: Functional Classification Sensory neurons (Afferent Neurons) - 0.9% of all neurons (retinal cells, olfactory epithelium cells) carry information from the sense organs to the brain Motor neurons (Efferent Neurons) 9% of all neurons (spinal motor neurons, pyramidal neurons, Purkinje cells) carry information from the CNS to muscles and glands Interneurons (only in CNS) have short axons (2) and communicate only within their immediate region

13. Sensory Neurons • INPUT Fromsensory organs to the brain and spinal cord. somatosensory neuron Vision, hearing, taste and smell nerves are cranial, not spinal Brain Sensory Neuron Spinal Cord

14. Brain Sensory Neuron Spinal Cord Motor Neuron Motor Neurons • OUTPUTFrom the brain and spinal cord To the muscles and glands.

15. Brain Sensory Neuron Spinal Cord Motor Neuron Interneurons • Interneurons carry information between other neurons only found in the brain and spinal cord.

17. Types of neurons: Classification based on Structure

21. Multipolar Neurons in the hippocampus - pyramidal Neurons in deeper layers of the cerebral cortex - pyramidal

22. Hippocampal inhibitory axons (yellow and green) can synapse on many neurons. Cell body and dendrites shown in red.

23. Purkinje cell- In cerebellum

24. Bipolar Cells Bipolar Cell - Retina Olfactory Epithelium

25. unipolar trigeminal ganglion (V Cranial nerve) - sensory

26. Glia – Supporting Cells • Glia vs Neurons: • Amount: 10-50X more than neurons • Smaller: 1/10 size of neurons (.1 mm to .oo4 mm) • Neurons have 2 "processes" (axons & dendrites)…glial cells: 1 • Neurons CAN generate electrical conduction...glial cells: NO? • Neurons HAVE synapses (neurotransmitters)...glial cells: NO

27. Glia – Supporting Cells • Found in Both CNS & PNS Provide physical & functional • Glial Cells Satellite Cells • Astrocytes - Schwann Cells • Oligodendrocytes • Microglia

28. Who had more Glial than the average bear? • Einstein’s brain had fewer neurons to glial cells than the normal brains (more glial cells for every neuron) • Weighed less than avg 1,400 g  1,230 g…thinner area 9 but greater density! • Sulci unusual pattern rt lt parietal lobe  spatial & math reasoning

29. Astrocyte (Astroglia) Star-shaped cells that provide physical and nutritional support for neurons: 1) provide nourishment to neurons by receiving glucose from capillaries 2) transport nutrients to neurons 3) clean up brain debris (phagocytosis: digest parts of dead neurons) 4. Guide the migration of developing neurons 5. Involved in the formation of the blood brain barrier 6.) hold neurons in place

30. Oligodendrocytes - Myelin sheath - Form segments of myelin to numerous neurons at once - Wrap around axon

31. Multiple Sclerosis Autoimmune Disease Muscle symptoms: Loss of balance Muscle spasms Numbness or abnormal sensation in any area Problems moving arms or legs Problems walking Problems with coordination and making small movements Tremor in one or more arms or legs Weakness in one or more arms or legs

32. Microglia: • - Smallest of the glial cells • Phagocytosis: cleaning up CNS debris • Protect the brain from invading microorganisms and are thought to be similar in nature to microphages in the blood system

34. Schwann cells - PNS • - cells wrap around nerve axons • a single schwann cell makes up a • single segment myelin sheath • -aid in cleaning up PNS debris • guide the regrowth of PNS axons: arrange themselves in a series of cylinders that serves as a guide for sprouts of regenerating axons • If one of these sprouts • encounters a cylinder the sprout • will grow through the tube at the • rate of 3-4 mm per day

35. Guide the regrowth of PNS axons Nodes of Ranvier • After significant injury • (C) - the nerve begins to degrade (anterograde) • - The axon and surrounding myelin break down • - The round mast cells and phagocytic macrophages interact with Schwann cells to remove injured tissue debris. As the degradation of the distal nerve segment continues • (D), connection with the target muscle is lost, leading to muscle atrophy and fibrosis. • Once the degenerative events are complete…. • (E), all that remains is a column of collapsed Schwann cells (bands of Büngner). Axon sprouts with a fingerlike growth cone advance using the Schwann cells as guides. • (F), After reinnervation the newly connected axon matures and the preinjury cytoarchitecture and function are restored. Normal Mast cell, phagocytes

36. Guillain-Barre syndrome destroys the protective covering of the peripheral nerves (myelin sheath), disabling the nerves from transmitting signals to the muscles.

37. Dark circles are schwann cells surrounding PNS axons: myelin sheath.